"Source Code" is like "Groundhog Day" in hell

Source Code is a gritty, dark and very entertaining slice of near-future science fiction. On the surface, it plays like a claustrophobic, marginally more humanistic version of one of 24's more imaginative episodes. There's a terrorist bomb of some kind, planted on a Chicago commuter train, and it's already gone off. More are expected to follow. How to stop them?

Enter Jake Gyllenhaal as Air Force vet Sgt. Colter Stevens who, as the film opens, awakens on the train, blurry and confused. He's sitting across from a pretty young woman, Christina (Michelle Monaghan), who insists he is not who he knows he is and recognizes him as a fellow commuter named Sean. Disoriented and flushed with unease, he's making little headway when an explosion blows him back into...where?

Another reality, it appears. Sgt. Colter awakens in a dank, dark cockpit of some kind, suited up and strapped into what looks like a flight simulator. A voice crackles over a dodgy video monitor, and then an image appears. It's military officer Goodwin (Vera Farmiga), who explains, haltingly, hurriedly, that Sgt. Colter is part of a secret project that allows him to return, again and again, to the scene of the initial bombing in the guise of the dead man Sean. It's a desperate bid to determine where the initial bomb was hidden and who the bomber was.

The catch? Colter has exactly eight minutes before the explosion blows his new self to bits. Again and again. It's Groundhog Day in hell.

Screenwriter Ben Ripley has front-loaded this trippy-smart sci-fi actioner with plenty of great feints and red herrings. Even Sgt. Colter's "real" situation is a mystery throughout most of the film. The last thing he remembers is being in combat in Afghanistan. Then there was an explosion, and suddenly he's back in this strange compartment with time running out for him and most of Chicago.

It's possible to guess where this will all end, but Source Code is nonetheless a model of the nail-biting, race-against-time-and-again template. And amidst the recursive conflagrations and sudden oblivions of director Duncan Jones' film lies a warm and human heart, predestined for doom but beating up a storm despite itself. Source Code is not nearly as complex and eerily existential as Jones' debut, Moon, but in its way it's an even more satisfying slice of identity-scrambled sci-fi.